Modeling credibilityAcoustic perceptual correlates of news reading by native and non-

native speakers

A. De Meo, E. Pellegrino, M. Pettorino, M. VitaleUniversity of Naples L’Orientale

Credibility assessment

• Message credibility is generally agreed to result from an interaction of – message characteristics (related to message

content, encompassing factors such as plausibility, internal consistency, and quality)

– receiver characteristics (e.g., cultural background, previous beliefs)

– source characteristics (e.g., expertise, trustworthiness, regiornal or foreign accent)

speaker’s accent

• Foreign accent, i.e. the acoustic features of an utterance (segmental and/or suprasegmental) perceptually different from the average production of a native speaker, may impact speaker’s credibility because it activates prejudices and stereotypes

research questions• What happens to credibility, when stereotypes

about non-native speakers are neutralized by presenting the message as created by a native speaker and simply delivered by a non-native speaker?

• Does foreign accent make the speech harder to be processed?

• Does this processing difficulty make the foreign accented speech harder to be believed as hypothesized by the theory of “processing fluency”?

processing fluency• According to the socio-psychological concept of

“processing fluency”, the way stimuli are judged depends on the cognitive load involved in the input processing.

(Oppenheimer 2008; Schwarz 2004, Reber & Schwarz, 1999 )

5 PERCEPTUAL TESTS (1275 listeners)

• Test 1: 4 voices (2 NS and 2 Chinese NNS C1 level, mild & strong FA); 301 Italian listeners

• Test 2: 5 female voices (1 NS and 4 NNS with a strong foreign accent, A2-B1 levels); 265 Italian listeners

• Test 3: test 1 voices, with tonal range and silent pauses artificially increased and decreased through WinPitch; 120 Italian listeners

• Test 4: test 2 voices, with errors and disfluencies removal, segmental duration and tonal range cloned from the native voice using Praat (transplantation); 270 Italian listeners

• Test 5: 1 female native voice, L1 Italian; 319 Italian listeners

research design

research design• test 1 and 2: NATURAL SPEECH - L2 Italian– Focus on degree of foreign accent:2 NNS with same L1, Chinese, male and female, same age, both advanced learners of L2 Italian (C1), differing only for the degree of foreign accent (F = strong, M = mild).– Focus on different L1s and on different L2 levels of

competence:4 NNS with a strong foreign accent, all female voices, same age, diverging for level of competence (two A2 and two B1), and L1s (A2: Arabic and Japanese, B1: Chinese and Vietnamese).

research design• test 3 and 4: SYNTHESIZED SPEECH - L2 Italian– Focus on prosody:

manipulation of tonal range and silent pauses (2 Chinese NNS and 2 Italian NS)

– Focus on segmental and suprasegmental anomalies:• segmental errors and disfluencies removal• segmental duration cloning from the native voice• tonal range cloning from the native voice(4 NNSs and 1 NS)

research design• test 5: NATURAL and SYNTHESIZED SPEECH - L1 Italian

– Focus on L1 anomalies and disfluencies:• transplanted disfluent speech• elicited disfluent speech(1 NS of Italian)

• bizarre-but-true news from around the world read in Italian

• organized in form of radio news magazines, pretending to make a survey on media reliability, in order to avoid to focus the attention on foreign voices

corpus

• degree of perceived accent (native accent, mild foreign accent, strong foreign accent)

• comprehensibility, i.e. listener’s estimation of difficulty in understanding an utterance (poor, sufficient, good)

• credibility of each news item (true, false)

perceptual assessment

RESULTS

test 1-4L2 Italian

0306090

"poor comprehensibility" "strong foreign accent"false

the worst non-native voice of the corpusArabic L1, A2 of L2 Italian - CEFR

• high percentage of disfluencies (35%)• low degree of comprehensibility (92% “poor”)

IT_M IT_F CH_M CH_F0

20

40

60

80

100

"poor comprehensibility" "strong foreign accent"false

NS and NNS (C1 of L2 Italian - CEFR)

• no disfluencies• high degree of comprehensibility (96-98% “good”)

TEST 1-4 (L2 Italian)

• variation in credibility is not exclusively dependent on the message content;

• credibility is rather delivered by the comprehensibility level of the utterance;

• comprehensibility, in turn, is primarily affected by the features often characterizing the L2 speech: the more the disfluencies, wrong pauses, interruptions and anomalous tonal variations, the lower the comprehensibility.

results

• The reason of the mistrust of the listener to the message should therefore not be sought in the opposition “foreign/native”, but rather in the degree of comprehensibility of the utterance and, therefore, in the level of difficulty encountered in its decoding.

results

What happens if the native speaker is as disfluent as the non-native speaker?

test 5 - L1 Italian

• 1 Italian NS (female)• corpus– 4 bizarre-but-true news– natural speech

• elicited disfluencies (reading distance: greater than the optimal)

• plain reading

– synthesized speech• transplantation of non-native anomalies and disfluencies

(Arabic speaker, A2 CEFR, highly disfluent) on the Italian plain reading

materials and methods

– Anomalies (segmental duration, pitch contour)

– Disfluencies (repetitions, vocalizations, nasalizations, interruptions, etc.)

transplanting NNS features

spoken time composition

17

2459

elicited disfluent speech

% silences % disfluencies% phonation

13

25

62

transplanted disfluent speech

% silences % disfluencies% phonation

• comparable speech time composition• segmental and prosodic differences

• 50 native Italian listeners– 2 groups

• 8 news– 4 transplanted disfluencies– 4 elicited disfluencies– 2 random orders (2 transp. + 2 elicit.)

• degree of foreign accent (FA)– native accent, mild foreign accent, strong foreign

accent

pretest

pretest

elicited transplanted0

102030405060708090

100

55

1

41

44

94

foreign accent degree (average values - %)

native accent mild foreign accent strong foreign accent

Chinese C10

20

40

60

80

100

0

47 53

• 319 listeners– 4 homogeneous groups, aged 21-24, M/F,

university students• 8 items - 4 different orders– 4 news - plain reading (PR)– 4 news - elicited disfluencies (ED)

• assessment– foreign accent (native accent, mild FA, strong FA)– comprehensibility (poor, sufficient, good)– credibility (true, false)

perceptive test

perceived accentglobal values - %

plain reading disfluent reading0

102030405060708090

100 96

52

4

43

05

native accent mild foreign accent strong foreign accent

comprehensibilityglobal values - %

plain reading disfluent reading0

102030405060708090

100 92

127

71

1

16

good sufficient poor

credibilityglobal values - %

plain reading disfluent reading0

102030405060708090

100

64

3736

63

TRUE FALSE

plain re

ading

disfluent r

eading

04080

native accent good comprehensibilityTRUE

first second0

20

40

60

80

100

plain reading (NS)

first second0

20

40

60

80

100

disfluent reading (NS)

in conclusion

• Current findings indicate that there is a direct relationship between comprehensibility and credibility, supporting the “processing fluency” theory

• Low comprehensibility affects credibility of both native and non-native disfluent speech

• A NNS having a strong foreign accent but an advanced level of L2 competence has the same chance of communication success of a NS, in terms of credibility

• There is only an indirect relationship between foreign accent and credibility, mediated by comprehensibility

ReferencesDe Meo, A. (2012), “How credible is a non-native speaker? Prosody and surroundings”,

in Methodological Perspectives on Second Language Prosody. Papers from ML2P 2012, Padova: CLEUP, pp. 3-9. http://www.maldura.unipd.it/LCL/ML2P/proceedings.html

De Meo, A., Pettorino, M., Vitale, M. (2012), “Non ti credo: i correlati acustici della credibilità in italiano L2”, in G.Bernini, C. Lavinio, A. Valentini, M. Voghera (a cura di) Atti dell’XI Congresso dell’Associazione Italiana di Linguistica Applicata, “Competenze e formazione linguistiche. In memoria di Monica Berretta”. Guerra Edizioni, Perugia, pp. 229-248.

De Meo, A., Vitale M., Pettorino, M., Martin, P., (2011), “Acoustic-perceptual credibility correlates of news reading by native and chinese speakers of Italian”, in Wai-Sum Lee e Eric Zee (eds.), Proceedings of the 17th International Congress of Phonetic Sciences, City University of Hong Kong, Hong kong, Cina, pp: 1366-1369.

Gluszek, A., Dovidio, J.F. (2010), “The way they speak: Stigma of non-native accent in communication”. Personality and Social Psychology Review 14, pp. 214-237.

Lev-Ari, S., Keysar, B. (2010), “Why don’t we believe non-native speakers? The influence of accent on credibility. Journal of Experimental Social Psychology 46, pp. 1093-1096.

Pettorino, M., De Meo, A., Pellegrino, E., Salvati, L., Vitale, M. (2011), “Accento straniero e credibilità del messaggio: un’analisi acustico-percettiva”, in B. Gili Fivela, A. Stella, L. Garrapa, M. Grimaldi (eds.), Contesto comunicativo e variabilità nella produzione e percezione della lingua, Proceedings of the 7th Conference of the Italian Association for Speech Sciences (AISV 2011), Roma: Bulzoni editore, CD (9 pp.).

Pettorino, M., De Meo, A., Vitale, M. (2012), “Transplanting credibility into a foreign voice. An experiment on synthesized L2 Italian", in H. Mello, M. Pettorino, T. Raso (eds.), Speech and Corpora, Proceedings of the 7th GSCP International conference, Firenze: Firenze University Press, pp. 281-284.

Reber, R., Schwarz, N. (1999), “Effects of perceptual fluency judgements of thruth. Consciousness and Cognition 8, pp. 338-342.

Thorne, S. (2005), “Accent pride and prejudices: Are speakers of stigmatized variants really less loyal?”. Journal of Quantitative Linguistics 12, pp. 151-166.

Thank you!